Vitamin D Insufficiency in Pre- and Early Adolescent Children

描述（由申请人提供）：我的长期目标是成为一名精通的独立临床研究人员，研究维生素D和钙营养的种族差异。我的职业发展计划包括获得临床研究理学硕士学位，并指导临床和社会研究。我计划研究青春期前和早期的非裔美国人和白种人儿童的维生素D状况。流行病学和临床数据表明，在美国成人和青少年中维生素D缺乏的患病率很高。对青春期前儿童维生素D缺乏的患病率、季节性变化和代谢影响知之甚少。在第一阶段，采用纵向研究设计，我们将估计6至12岁儿童维生素D不足的患病率和季节性变化，并描述其对骨代谢的影响。将在夏季（6月至9月）和冬季（12月至3月）对140名健康的青春期前和早期儿童（6-12岁，Tanner I或II，非裔美国人[n=94]和高加索人[n=46]）进行研究。将在夏季和冬季评估维生素D状况、钙化激素和骨转换标志物。其他指标包括饮食中维生素D和钙的摄入量、阳光照射和体重指数。本研究将有助于确定非裔美国人和白种人学龄儿童维生素D缺乏的患病率、季节性变化、代谢影响。在2168期（非裔美国人：84人，高加索人：84人）中，8至14岁的青春期前和青春期儿童将在秋季和冬季（10月至3月）开始为期6个月的随机安慰剂对照试验（RCT）中每天服用维生素D31000 ID与安慰剂。本研究将确定血清25(OH)D的临界值，以确定维生素D不足的定义，并记录治疗维生素D状态的安全性和有效性。为了解决健康差异的问题，我们将使用研究设计来检验假设，即与白人儿童相比，父母对医学和研究的不信任是招募非裔美国儿童进入临床研究的障碍。参与维生素D研究的孩子的父母将接受调查。同意和不同意的父母之间信任指数的差异将被确定。研究结果应有助于制定克服这些障碍的战略。预防儿童维生素D不足将改善他们的骨骼健康（增加骨量峰值），并减少他们成年后的“骨质疏松症负担”。优化非裔美国儿童的维生素D状态可能有可能减少与慢性维生素D不足相关的非骨骼疾病（如糖尿病和前列腺癌）的差异，这些疾病对非裔美国成年人的影响尤为严重。

DESCRIPTION (provided by applicant): My long- term goal is to become a proficient independent clinical researcher addressing racial and ethnic differences in vitamin D and calcium nutrition. My career development plan includes a Master of Science in Clinical Research and mentored clinical and social research. I plan to study the vitamin D status of pre- and early adolescent African American and Caucasian children. Epidemiologic and clinical data document a high prevalence of vitamin D insufficiency among adults and adolescents in the US. Little is known about the prevalence, seasonal variation and the metabolic impact of vitamin D insufficiency in preadolescent children. In Phase 1, using a longitudinal study design, we will estimate the prevalence and seasonal variation of vitamin D insufficiency in children 6 to 12 years old and characterize its impact on bone metabolism. A cohort of 140 healthy pre- and early adolescent children (6-12 yrs old, Tanner I or II, African American [n=94] and Caucasian [n=46]) will be studied during summer (June through September) and winter (December through March). Vitamin D status, calcitrophic hormones and markers of bone turnover will be assessed during summer and winter. Other measures include dietary intakes of vitamin D and calcium, sun exposure and body mass index. This study will help establish the prevalence, seasonal variation, metabolic impact of vitamin D insufficiency in young school-age African American and Caucasian children. In phase 2,168 (African American: 84, Caucasian: 84) 8 to 14 year old preadolescent and adolescent children will undergo a randomized-placebo controlled trial (RCT) of vitamin D31000 ID daily vs. placebo for 6 months initiated during fall and winter (October through March). This study will determine the serum 25(OH)D cutoff for the definition of vitamin D insufficiency and document the safety and efficacy of treatment on vitamin D status. To address issues of health disparities we will use the study design to test the hypothesis that parental mistrust in medicine and research is a barrier to recruitment of African American children into clinical research compared to Caucasian children. Parents of children recruited for the vitamin D study will be surveyed. Differences in the trust index between consenting and declining groups of parents will be determined. The results should help develop strategies for overcoming those barriers. Prevention of vitamin D insufficiency in children will improve their bone health (increase the peak bone mass) and reduce their "osteoporosis burden" during adulthood. Optimizing vitamin D status in African American children may have the potential to reduce the disparities from non-skeletal disorders associated with chronic vitamin D insufficiency such as diabetes and prostate cancer that disproportionately affect African American adults.